CN110799037B

CN110799037B - Oven with smoke supply device

Info

Publication number: CN110799037B
Application number: CN201880042090.7A
Authority: CN
Inventors: 保卢斯·约翰斯·维布鲁根; 杰克布斯·裴雏斯·哈博图斯·哈克斯
Original assignee: GEA Food Solutions Bakel BV
Current assignee: GEA Food Solutions Bakel BV
Priority date: 2017-06-23
Filing date: 2018-06-25
Publication date: 2022-06-03
Anticipated expiration: 2038-06-25
Also published as: EP3641549B1; JP2020524505A; RU2020100794A; RU2020100794A3; EP3641549A1; US20200404933A1; CN110799037A; CA3068129A1; US11980201B2; WO2018234581A1; ES2902223T3; BR112019025410A2; RU2764457C2; PL3641549T3

Abstract

The present invention relates to an oven comprising: first and second chambers, each provided with a heater to heat the gas of the cooking product; at least one gas circulation device establishing gas circulation in a chamber; an endless conveyor for conveying the product from the inlet through the chamber to the outlet, wherein the conveyor is at least partially arranged in a helical path; a separating means for separating the first and second chambers, wherein the transfer means passes through the separating means; and a gaseous natural smoke supply device for supplying gaseous smoke to at least one of the chambers, wherein the smoke supply device is arranged upstream of the circulation device.

Description

Oven with smoke supply device

Technical Field

The present invention relates to an oven comprising:

at least one chamber, each chamber being provided with at least one heater to heat the gases of the cooking, drying and/or baking product,

at least one gas circulation device, each chamber being provided with at least one gas circulation device, gas circulation being established in the chamber,

an endless conveyor for conveying the product from the inlet through the chamber to the outlet, wherein the conveyor is at least partially arranged in a helical path,

preferably a partition means, separating the first and second chambers, wherein the transfer means passes through the partition means,

and a gaseous natural smoke supply device which supplies gaseous smoke to at least one of the chambers.

Background

For example, US6203834B1 discloses an oven of this type. However, there is a constant desire by those skilled in the art to improve the smoke distribution and/or safety performance of such ovens.

Disclosure of Invention

This problem is solved by an oven comprising:

at least one chamber, each chamber being provided with at least one heater to heat the cooking, drying and/or baking product gases,

and a gaseous natural smoke supply device for supplying gaseous smoke to at least one of the chambers.

Wherein the smoke supply means is disposed upstream of the circulation means.

Due to the arrangement of the gaseous smoke supply means upstream of the circulation means, an improved distribution and an improved safety performance are achieved.

The oven comprises at least one cavity, preferably two cavities. In each chamber, the product is cooked, dried, baked and/or browned. In case there are two chambers, the two chambers may be separated from each other by a separating means, so that different dry-bulb temperature and/or humidity/dew-point temperature conditions may be set in the two chambers. For example, the partition is a wall between the two chambers, which is sealed, preferably hermetically sealed, to the oven housing. However, the separating means is provided with openings/channels therein through which the conveying means can pass. Preferably, the separating means is insulated to reduce heat transfer between the two chambers. The passage may simply be an opening in the partition means or a duct extending to at least one of the chambers, preferably both chambers or a duct connecting both chambers. Preferably, the two chambers are equal in size.

In one chamber, a product inlet is provided and a product outlet is located in the same or another chamber. Each chamber has a gas, preferably air and/or water vapour, heated by a heater and preferably adjusted to a specific dry bulb temperature. Each heater in each chamber is preferably individually controlled. The gas heats the product to be cooked, dried and/or roasted by conduction and/or convection. The gas is preferably a mixture of air, water vapour and smoke herein.

The gas is circulated in each chamber by circulation means, such as a fan, which carries the gas out of the chamber, preferably sucking it out, and forces it back into the same chamber. Each fan is preferably controlled individually. Preferably, each chamber is provided with at least one distributor which distributes the circulation gas supplied by the circulation means in the chamber. Preferably along the vertical height of the chamber. The distribution may be uniform along the entire height of the chamber or may vary with the height of the chamber. Preferably means are provided to control the gas distribution along the height of the chamber. In addition, or alternatively, each chamber is provided with a collector which collects the recycle gas before it enters the recycling apparatus. The collection is preferably performed at different vertical positions. The collection may be uniform along the entire height of the chamber or may vary with the height of the chamber. Preferably means are provided to control gas collection along the height of the chamber.

Preferably, each chamber is provided with at least one heater, which is individually operable so that the dry bulb temperature in each chamber can be adjusted individually in each chamber. The heater is preferably arranged downstream of the circulation device. The dew point temperature of the gas in each chamber may be the same or different. Each chamber may include a separate dew point temperature, which may be the same or different. The dew point temperature in the respective chamber can be influenced by an inlet for gas, preferably air and/or fluid, preferably steam, wherein the gas dew point temperature is lower than the gas in the respective chamber and the fluid dew point temperature is higher than the gas in the respective chamber.

The product is conveyed from the inlet through one or more chambers to the outlet by an endless conveyor to pass through the oven of the present invention, wherein the conveyor is at least partially disposed in a helical path. Preferably, the conveyor comprises two helical paths connected by a straight segment, the straight segment being located adjacent to the separating means, herein the straight segment is in the channel. This embodiment is particularly preferred in case there are two chambers. The transfer means is preferably an endless conveyor belt, more preferably at least partially permeable to the fluid being treated. Preferably, the conveyor is continuous upward.

The oven preferably includes dry-bulb temperature and/or humidity/dew-point temperature control means for controlling the dry-bulb temperature and/or humidity/dew-point temperature of the fluid in each chamber respectively. The dry bulb temperature of the fluid is regulated by heaters, in embodiments where at least one heater is provided in each chamber, preferably two heaters are provided in each chamber, the heaters can be individually regulated. As mentioned above, the humidity/dew point temperature of the fluid is adjusted by adding steam or fresh gas, preferably air, having a low humidity/dew point temperature.

According to the invention, the oven comprises a gaseous natural smoke supply device which supplies gaseous smoke to at least one chamber, preferably two chambers. The natural smoke of the device according to the invention is not supplied as a fluid, but the smoke generated in the smoke generator, for example, from wood chips, is then supplied directly to the oven of the invention. The smoke generator may be inside the oven or outside the side of the oven. Preferably, two or more smoke generators are provided, which provide natural smoke. The smoke generator and the cooking/drying chamber are interconnected by one or more ducts.

In an embodiment of the invention based on an oven, preferably comprising two different environmental zones/chambers, wherein the conveyor comprises a spiral path, a straight path followed by a spiral path, a second spiral path followed by a straight path, the products are to be treated with gaseous fumes in a first zone and/or treated with gaseous fumes in a second zone. Preferably, the two zones differ in their environmental conditions such as dry bulb temperature and/or humidity/dew point temperature.

Different treatments may be applied in different regions/chambers of the oven. In an embodiment of the invention, the product will be dried in a first zone/chamber and will be smoked by gaseous smoke in a second zone/chamber. In another embodiment of the invention, the product will be dried in the first zone/chamber and will be smoked in the second zone/chamber by gaseous smoke and/or liquid smoke. In yet another embodiment of the present invention, the product will be treated with liquid smoke in the first zone and/or will be treated with gaseous smoke in the second zone, or vice versa, wherein the food product will be smoked with gaseous smoke in the first zone and treated with liquid smoke in the second zone.

According to the invention, the natural fumes in the gaseous state are supplied to the chamber upstream of the circulation device, with respect to the flow of the circulation gas. Preferably, the gaseous natural smoke is provided at and/or near the inlet of the circulation device. The gaseous natural smoke may be supplied under pressure or may also be drawn into the circulation device.

The endless conveyor, in particular its helical path, is preferably arranged around preferably hollow rollers, wherein each chamber preferably comprises one roller. Preferably, the drum comprises openings on its outer circumference through which circulation can take place. The openings are preferably distributed along the vertical height of the drum. The circulating gas may enter the drum from the chamber through these openings or exit the drum into the chamber through these openings. The fumes may be supplied to the inside of the drum. The top end of the drum is preferably connected in an air-permeable manner to a circulating device, which, for example, sucks the gas from the drum and forces it back into the same chamber from which it was carried. The circulation means is preferably arranged on top of the drum or above the drum.

In the case of a collector/distributor, in particular a collector, gaseous natural fumes can be supplied to the interior of the collector/distributor. The top end of the collector/distributor is preferably connected in a ventilating manner to a circulating means, for example, which entrains gas from the collector/distributor, preferably sucks it out, and forces it back into the same chamber from which it was entrained. The circulation means is preferably located at or above the top of the collector/distributor.

In the circulation device, the gaseous natural fumes are mixed with the circulation gas, which is then fed back into the chamber where it is preferably distributed.

According to a preferred embodiment, the duct extends from the gaseous natural smoke supply means, preferably through a bottom section of the drum and/or collector/distributor, to the drum and/or collector/distributor.

Preferably, the oven of the invention comprises a plurality of drums and/or a plurality of collectors/distributors, in particular two drums per oven and two collectors/distributors per chamber. Gaseous natural fumes can be supplied to each chamber by each drum and/or collector/distributor. Preferably, the gas natural smoke supply of each drum and/or collector/distributor is individually controllable. The adjustments can be made by the control means and, for example, manually or automatically according to a certain recipe, which can be stored in the PLC. The oven can be automatically adjusted by the PLC as long as the recipe is changed.

This can be achieved by individually setting and/or adjusting the distance between the downstream end of the conduit and the inlet of the circulation device. For example, adjustment can be made by telescoping tubes.

Additionally, or alternatively, the oven of the invention comprises at least one regulating valve, which is set manually, and/or by means of a PLC, and/or, in case the natural smoke supply means comprise a compressor, preferably controls the compressor.

According to a preferred embodiment, an exhaust is provided to remove gas from the oven, preferably from the inlet and/or the outlet. By means of these exhaust means, it is possible to avoid that gases, such as gases containing smoke, flow from the oven to the surroundings.

Preferably, the oven comprises means for supplying air from the ambient to at least one cavity/area of the oven. The ambient air has a lower temperature and/or dew point and/or smoke content than the gas in at least one cavity/region within the oven. The present preferred embodiment allows for the regulation of smoke content and/or temperature and/or dew point in at least one cavity/region of the oven. If air from the environment is added, the exhaust air is preferably vented from the oven through at least one exhaust.

Preferably, the leakage occurring between the two chambers/regions is controllable. Such a controlled leakage may be caused by a pressure gradient between the two chambers and/or by means provided in the connection between the two chambers. Due to the leakage, the temperature-dew point-and/or smoke concentration gradient between the two chambers may decrease.

Another subject of the invention is a method of operating an oven comprising:

a gaseous natural smoke supply (10) for supplying gaseous smoke to the at least one chamber,

wherein the fumes are supplied upstream from the circulation device.

The disclosure with respect to the present subject matter also applies to other subject matters and vice versa. Preferably, an exhaust is provided to remove gas from the oven, preferably from the inlet and/or outlet.

Preferably, the method comprises supplying air from the environment, preferably gas having a temperature and/or dew point and/or smoke content lower than that in at least one chamber/region of the oven, to the oven, preferably to only one chamber/region of the oven.

Preferably, a controlled leakage occurs between the two chambers/regions.

Drawings

Next, the present invention will be explained with reference to the drawings. These descriptions do not limit the scope of protection.

Fig. 1-3 illustrate an embodiment of the oven of the present invention.

Fig. 4 shows an embodiment in which the smoke flow is guided in some way.

Figure 5 shows an embodiment in which the smoke generator is located in a separate production room.

Detailed Description

Fig. 1-3 illustrate the oven of the present invention. The oven 11 of the present invention comprises a first chamber a and a second chamber B. One chamber A, B may be sufficient, as understood by those skilled in the art. The chambers are separated by a partition 7, such as a metal wall, preferably an insulating partition, which is sealed to the housing of the oven. The oven comprises a conveyor 4 which conveys the product to be cooked, dried and/or roasted through the oven. The conveyor 4 of the present invention is run by a spiral conveyor in each chamber A, B connected by straightaway sections adjacent to the partitions 7. If only one chamber is provided, the chamber preferably has a spiral conveyor. In each of these chambers a rotatable drum 12 is provided, around which drum 12 the conveyor belt 4 is guided along a helical path. The endless conveyor enters the oven 11 through an entrance 8 in the oven housing, preferably through a straight conveyor section, and exits the oven 11 through an exit 9 in the housing, also preferably through a straight section. The two spiral sections are preferably connected by a straight conveyor section at the top. In case only one chamber is provided, the outlet 9 is located in the same chamber as the inlet. The conveyor belt is preferably permeable to the gases being treated, such as air and steam, and the fumes of this embodiment. The separating means 7 comprise a passage for the conveyor belt section between the two spiral paths. Preferably, the conveyor is operated continuously.

The gas in the oven, which is preferably a mixture of air and steam, is heated by a heating device, indicated as a whole with 2, which is arranged on top of the housing. Each chamber is preferably provided with a heating means, more preferably the heating means are individually controllable. Each of these heating means 2 comprises at least one recirculation means, which in this embodiment comprises two recirculation means, i.e. two fans in this embodiment. In this embodiment, there are two recirculation devices per chamber A, B, although one recirculation device per chamber may be sufficient as understood by those skilled in the art. The fluid flow rate and the corresponding degree of recirculation of each circulation device can be adjusted individually. The gas is carried out, preferably sucked, from each chamber A, B by the circulating means 3 and forced back into the same chamber A, B from which it was carried out.

In an embodiment the chamber further comprises a gas collector/distributor 13, in this embodiment a vertical duct/channel with openings, the collector/distributor 13 being distributed along the height of the duct/channel, the collector/distributor 13 collecting gas from each chamber and providing the collected gas to the circulation means 3. In the present embodiment, two collector/distributors 13 are provided. Each collector/distributor 13 is in this embodiment connected to a separate recirculation means 3.

In this embodiment, the gas enters the hollow of the gas collector/distributor 13 via the conveyor 4, which conveyor 4 conveys the product and is disposed around the enclosed rotatable drum 12 in this embodiment. The recirculation channel is indicated by the arrow marked with reference C. The gas of this embodiment flows through the heating element 2 and is then circulated through the drum 12 of each chamber into the individual chambers a, B. Before the gas is reintroduced into the individual chambers, the gas flow can be distributed according to a desired pattern, in particular at the vertical level of the drum, by means of distribution means provided in the drum, for example as openings, the section of which is preferably adjustable to influence the distribution of the gas. It will be appreciated by those skilled in the art that the flow path of the gas indicated by arrow C may also be reversed, i.e. the gas is forced into and dispensed by the dispenser 13 and then flows through the chamber and is collected by the drum. Then, the inlet of the circulation device 3 is connected to the inner diameter of the drum.

In both chambers A, B, different dry bulb temperature and/or humidity/dew point temperature conditions may be set.

Inventively, the oven comprises a gaseous natural smoke supply 10, which supplies the smoke as a gas. Preferably, the smoke is generated by burning wood chips or the like. Preferably, liquid smoke is not used. The smoke is preferably generated by a smoke generator (not shown) and then preferably immediately used in the oven of the present invention. The smoke supplying means may comprise a compressor to increase the pressure of the natural smoke in the gaseous state. Preferably, the compressor is controllable. The smoke supply 10 is connected to ducting which directs the smoke of the present embodiment to each chamber, in the present embodiment at two different locations. A duct system connects the hollow of the collector/distributor 13 with the smoke supply and in this embodiment each duct extends to the hollow of the collector/distributor 13. In particular, as shown in fig. 1, the length of the conduits and the distance E between the downstream end of the conduits 5.1-5.4 and the inlet of the recirculation device are different. In the case where the pressure level on the suction side of the circulation device 3 is lower than the ambient pressure, the driving force decreases with increasing distance E, so that the amount of smoke sucked through each duct is different. The smoke is least transported to the rightmost duct and most transported to the adjacent duct. Assuming that the two circulation means 3 operate under the same conditions, the two ducts leading to the left convey the same amount of fumes, since their distance E is the same.

Further or alternatively, one or more valves 6.1-6.4 may be provided to manually or automatically adjust the amount of smoke provided through each duct. Still further or alternatively, the pressure of the supply of natural gaseous fumes may also be controlled to adjust the overall supply and/or distribution to the ducts 5.1-5.4. In an alternative embodiment, the amount of smoke may be reduced by connecting a reducing means, such as a conical element, to the smoke duct 5.1-5.4, preferably to the top end of the duct, where the gaseous smoke is discharged from the smoke duct.

In the embodiment according to fig. 3, there is only one central valve 6.7, controlling the overall supply to the oven.

The fumes are supplied to the recirculation means together with the recirculated gas, compressed by the recirculation means 3, then heated by the heat exchanger 2, and then recirculated back into the chamber from where the fumes are drawn. As long as the recirculation device 3 is operating, the supply of smoke on the inlet side of the recirculation device is such that the newly added smoke mixes well with the recirculated gas and no dense smoke enters the environment, because the pressure level on the upstream side of the recirculation device is preferably lower than ambient pressure.

Fig. 1 and 4 show the flow pattern of the recirculating airflow, i.e., smoke. It can be seen that the gas flow passes through different levels of the spiral path, the direction of which is substantially horizontal. In this example, the air flow is from the outside to the inside of the spiral. As shown in fig. 4, for example, the product 27, such as a meat product, is rotated in a helical path with respect to the flow direction of the smoke, so that the smoking level is equal in all parts of the product.

Fig. 5 shows an embodiment in which the smoke generator 14 is preferably not located in the production chamber 17 comprising the oven 11, but is preferably located in a separate production chamber 14. This prevents combustion gases generated by smoldering the wood chips in the smoke generator from entering the production chamber 17.

In a preferred embodiment, the sensing means 22, such as a pressure device, of the smoke generator 14 is provided in the smoke supply line 25 of the smoke generator to the oven. If a pressure device is provided, the pressure drop may be measured, for example, on a supply line within the smoke generator and/or on a supply line from the smoke generator to the oven and/or at other locations of the smoke supply to the oven. Depending on the pressure drop, the smoke supply may be reduced and if a predetermined pressure drop is exceeded, the combustion in the smoke generator may be stopped by stopping the supply of oxygen/fresh air to the combustion chamber and/or extinguishing the combustion chamber.

In another or additional preferred embodiment, the ratio of fresh air/combustion gas supplied to the oven 11 will be determined directly and/or by measuring the gas composition, preferably at least 20: 1. Depending on the fresh air supply rate and/or the combustion in the smoke generator 14, the process can be controlled to keep the rate within the correct range. If the predetermined ratio range is exceeded, for example, due to a failure of the fresh air supply in the smoke generator, so that the combustion gases in the smoke generator are too high, the smoke generator can be stopped. The supply of fresh air may preferably be measured and/or determined using means 21 such as pressure sensing means and/or volume flow measurement. Another detection device that may be used is a carbon monoxide or carbon dioxide detector. In case a predetermined value is exceeded, for example the volume fraction of carbon monoxide exceeds a predetermined value, the smoke generator may be stopped.

In another preferred embodiment, the supply of fresh air to the smoke generator/the supply of fresh air inside the smoke generator will be such that the air will pass through one single air supply source and will be distributed by the separating means to the combustion chamber and the distribution chamber respectively. In the distribution chamber, the flue gas from the combustion chamber and the fresh air will be mixed to a ratio of preferably at least 20: 1. The generated gaseous fumes will be supplied from the distribution chamber to the oven.

In a further preferred embodiment, the operation of the fans 20.1 and 20.2, preferably located at the top of the production facility, can be monitored. An exhaust duct 19.1, the interior of which communicates with the inlet 8, and an exhaust duct 19.2, the interior of which communicates with the oven outlet 9, enable the gases to be evacuated from the oven 11, for example by suction by fans 20.1 and 20.2, respectively. If the fans 20.1 and 20.2 do not work properly, the gas from the oven will flow into the production chamber 17 through the inlet 8 and/or the outlet 9 of the oven. The proper operation of the fan may be determined by measuring the number of revolutions of the fan, for example, using a pulse counter. If the measured number of revolutions differs from a predetermined value, the control unit will switch off the smoke generator.

In another preferred embodiment, the sensing devices 23.1 and 23.2 may be used to measure the gas flow in the exhaust pipes 19.1 and 19.2, respectively. If the fans 20.1 and 20.2 are operating normally and/or the valve means 26.1 and 26.2 are sufficiently open, the control unit may conclude that a gas leak has occurred from the oven to the production chamber 17, for example via the inlet 8 and/or the outlet 9 and/or the inlet of fresh air eventually supplied by the oven, in case the volume flow and/or the pressure drop is below a predetermined value. In this case, the smoke generator may be turned off.

In another preferred embodiment, the sensing means 24.1, e.g. the means for detecting the combustion gas/fresh air ratio to be applied, may be located inside/outside the inlet 8 and/or the sensing means 24.2 may be located inside/outside the outlet 9 of the oven 11. Other detection means that may be used are carbon monoxide detectors or carbon dioxide detectors. If the gas composition does not meet the predetermined value range, the smoke generator should be controlled to adjust the gas composition and/or to shut down the smoke generator.

In another preferred embodiment, the sensing means 24.1 and/or 24.2 are capable of detecting gas leakage from the inlet 8 and/or the outlet 9. If one or more sensing means, such as a temperature sensor and/or a pressure sensor, detects that a predetermined value is exceeded, the valves 26.1 and 26.1 in the exhaust line may be opened and/or further opened to control the discharge of gas until the detected value is within a predetermined value range. If the predetermined value range is exceeded, the smoke generator is switched off. During smoking in the respective chamber, the temperature may preferably be in the range of 60 ℃ to 120 ℃, well below the temperature of a conventional oven environment.

The operation of the fan 3 in the oven may be monitored by sensing means such as the operation of the fan motor. If the gas density in the oven increases (as may be part of the measurement) and the ratio of fresh air/combustion gas exceeds a predetermined value, the risk of explosion may increase, preferably shutting down the smoke generator. In another embodiment, the CIP (clean in place) supply line and the connected CIP nozzles integrated in the oven 11 for cleaning the oven may be used in an accidental situation, for example in case of a fire detected. The detection may be performed by a detection means such as a temperature sensor.

The sensing means 23 and/or 24 in combination with the valve means 26 and the fan 20 can further improve the energy efficiency of the smoking process.

If smoke, steam and/or ambient air is added to the oven, gas from one or both chambers may be vented from the oven through one or more vents. Smoke, steam and/or ambient air added to the oven may be used to create the desired leakage between the two chambers/regions of the oven.

Claims

1. An oven (11) comprising:

at least one chamber (A, B) each provided with at least one heater (2) to heat the gases of the cooking, drying and/or baking product,

at least one gas circulation device (3), at least one gas circulation device (3) being provided in each chamber, a gas circulation (C) being established in the chambers (A, B),

an endless conveyor (4) for conveying a product from an inlet (8) through the chambers (A, B) to an outlet (9), wherein the endless conveyor is at least partially arranged in a helical path,

a gaseous natural smoke supply (10) supplying gaseous smoke to at least one of the chambers (A, B),

wherein the fume supply means (10) is arranged upstream (D) of the gas circulation means, characterized in that the oven comprises a collector/distributor (13), which collector/distributor (13) collects and/or distributes the circulating gas in the chamber (a, B), wherein a duct (5.1-5.7) extends from the gaseous fume supply means (10) into the drum (12) and/or the collector/distributor and supplies fumes to the interior of the drum and/or the collector/distributor, wherein the distance (E) between the end of the duct (5.1-5.7) and the inlet of the gas circulation means (3) is adjustable.

2. Oven (11) according to claim 1, characterized in that it comprises a separating device (7) to separate the first and second chambers (a, B), wherein said carousel (4) passes through said separating device (7).

3. Oven (11) according to claim 1, characterized in that the oven (11) comprises two chambers (a, B).

4. Oven (11) according to claim 1, characterized in, that the endless conveyor (4) is arranged around a hollow drum (12).

5. Oven (11) according to claim 1, characterized in that said fumes are supplied to the inside of said drum (12).

6. Oven (11) according to claim 1, characterized in that said fumes are supplied to said collector/distributor (13).

7. Oven (11) according to one of the preceding claims, characterized in, that the oven (11) comprises a controllable smoke supply system comprising at least one regulating valve (6.1-6.7) and/or an adjustable smoke supply (10).

8. Oven (11) according to claim 1, characterized in that exhaust means (19.1, 19.2, 20.1, 20.2) are provided to remove gas from the oven.

9. Oven (11) according to claim 1, characterized in, that exhaust means (19.1, 19.2, 20.1, 20.2) are provided to remove gas from the inlet (8) and/or the outlet (9).

10. Oven (11) according to claim 1, characterized in that the oven (11) comprises means for providing air from the environment to the oven, the temperature and/or dew point and/or smoke content of which is lower than the gas in at least one cavity/zone (a, B) of the oven.

11. Oven (11) according to claim 1, characterized in that the oven (11) comprises means for providing air from the environment to only one chamber/area (a, B) of the oven, the temperature and/or dew point and/or smoke content of the air being lower compared to the gas in at least one chamber/area (a, B) of the oven.

12. Oven according to claim 1, characterized in, that the leakage occurring between the two chambers/zones (a, B) is controllable.

13. A method of operating an oven (11), comprising:

at least one gas circulation device (3), each chamber being provided with at least one gas circulation device (3), a gas circulation (C) being established in the chamber (A, B),

a gaseous natural smoke supply (10) supplying gaseous smoke to at least one of said chambers (A, B),

characterized in that the fumes are supplied upstream (D) from the gas circulation device, wherein the oven (11) comprises a collector/distributor (13), which collector/distributor (13) collects and/or distributes the circulating gas in the chambers (A, B), wherein a duct (5.1-5.7) extends into the drum (12) and/or the collector/distributor, and the distance (E) between the end of the duct (5.1-5.7) and the inlet of the gas circulation device (3) is adjustable.

14. Method according to claim 13, characterized in that the oven (11) comprises a separating device (7) separating the first and second chambers (a, B), wherein the endless conveyor (4) passes through the separating device (7).

15. Method according to claim 13, characterized in that an exhaust (19.1, 19.2, 20.1, 20.2) is provided to remove gas from the oven.

16. Method according to claim 13, characterized in that an exhaust (19.1, 19.2, 20.1, 20.2) is provided to remove gas from the inlet (8) and/or the outlet (9).

17. Method according to claim 13, characterised in that the oven comprises means for providing air from the environment to the oven, the temperature and/or dew point and/or smoke content of which is lower than the gas in at least one cavity/zone (a, B) of the oven.

18. Method according to claim 13, characterized in that the oven comprises means for supplying air from the environment to only one chamber/zone (a, B) of the oven, the temperature and/or dew point and/or smoke content of the air being lower than the gas in at least one chamber/zone (a, B) of the oven.

19. Method according to claim 13, characterized in that the leakage occurring between the two chambers/zones (a, B) is controlled.